In the related art, a substrate processing apparatus that processes a substrate such as, for example, a semiconductor wafer or a glass substrate, by supplying a processing liquid to the substrate is known.
A processing liquid used in the substrate processing apparatus may be produced by mixing a plurality of liquids in a predetermined ratio. In such a case, the substrate processing apparatus includes a mixing apparatus that produces the processing liquid by mixing the plurality of liquids.
A mixing apparatus described in Japanese Patent Laid-Open Publication No. 2003-275569 includes a mixing tank in which a plurality of liquids are mixed, a flow rate control unit that supplies the plurality of liquids to the mixing tank by a predetermined amount, a supplying time control unit that performs a control such that time lengths of supplying the plurality of liquids to the mixing tank become equal to each other.
Further, Japanese Patent Laid-Open Publication No. 2009-172459 discloses a mixing apparatus configured to supply each liquid to a mixing tank after all the liquids reach a predetermined flow rate so that a processing liquid with a predetermined mixing ratio may be produced from the beginning of supplying the liquids.